Raisaite is a rare copper magnesium selenite mineral occurring as delicate blue acicular sprays. It is found in the oxidized zones of selenium-rich hydrothermal ore deposits and is highly prized by advanced mineral collectors for its vivid color and rarity.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Raisaite

Hardness: ~2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this raisaite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch raisaite with a known reference. Raisaite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: bright sky-blue.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular crystals, radiating clusters.

Often confused with

Raisaite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Chalcomenite

Mohs 2-2.5

How to tell apart: Streak differs, so Raisaite leaves white, Chalcomenite leaves light blue.

How to tell apart: Streak differs, so Raisaite leaves white, Ahlfeldite leaves light green.

Compare →

Often found alongside raisaite

Minerals reported to co-occur with raisaite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CuMg[TeO₄(OH)₂](H₂O)₆
Mohs hardness: ~2
Density: 2.82 g/cm³
Colors: Bright sky-blue
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Acicular crystals, radiating clusters
Cleavage: Imperfect on {100}
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in the oxidation zone of polymetallic sulfide and telluride-bearing veins

Where rockhounds find raisaite

Classic worldwide localities

Sentyabr’skoe deposit, Ilirney district, Western Chukotka, North-Eastern Russia

Field-hunting tip

Where it forms: A secondary mineral in the oxidation zone of polymetallic sulfide and telluride-bearing veins. If you start seeing gypsum, malachite, azurite in float, you are in the right ground. Typical habit: acicular crystals, radiating clusters. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify raisaite?+

Mohs hardness is ~2. Luster: vitreous. The streak is white. Common colors include bright sky-blue.

Where is raisaite found?+

Notable localities include Sentyabr’skoe deposit, Ilirney district, Western Chukotka, North-Eastern Russia.

Is raisaite safe to handle?+

Raisaite contains copper. Contains copper and selenium; wash hands thoroughly after handling and avoid inhaling dust or ingesting particles.

What rocks look like raisaite?+

Raisaite is most often confused with Chalcomenite, Ahlfeldite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with raisaite?+

Raisaite commonly co-occurs with Gypsum, Malachite, Azurite, Cerussite, Anglesite, Brochantite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does raisaite form in?+

Where it forms: A secondary mineral in the oxidation zone of polymetallic sulfide and telluride-bearing veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is raisaite used for?+

Raisaite is used in collector.

Find raisaite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.